The present invention relates to an FRP racket frame and a method for producing the same, and more particularly relates to improvements in physical property and shaping fitness of a fiber reinforced plastic (hereinafter referred to as "FRP") racket frame of a tubular construction used for tennis or badminton games.
Such an FRP racket frame contains, for example, fibers dispersed in a matrix of thermosciting synthetic resin such as epoxy resin. One typical example of such an FRP racket frame of a tubular construction is proposed in Japanese Patent Opening Sho. 54-152536, in which a racket frame is made of prepreg material, i.e. an incompletely solidified product containing fibers impregnated with matrix resin. An elongated tubular crude product made of such a prepreg is placed in position in a mould and heated under pressure while applying internal pressure to the tubular crude product for shaping.
In the case of such a conventional production process, however, it is necessary to drill a lot of string holes transverse the body of a racket frame after shaping. Separate formation of such string holes after shaping much lowers efficiency in production and presence of such string holes degrades mechanical strength of tile product seriously.
After formation of the string holes, strings are set to the racket frame in tension past tile string holes. Due to presence of sharp edge openings of the string holes developed by drilling, the strings in tension tend to cut during setting to the racket frame.
In an attempt to evade such cutting through contact with the sharp edge openings, it is already proposed to cover each sharp edge opening with a grommet made of soft synthetic resin such as nylon. Use of such grommets, however, complicates the production process and increases the production cost.